如何在swift

Question

我使用以下代码绘制线条。线条边缘有点，我想在用户点击结束点时显示工具提示。 代码段在下面，

 override func drawRect(rect: CGRect) {
        // Drawing code
      UIColor.brownColor().set()
    let context = UIGraphicsGetCurrentContext()
    //CGContextSetLineWidth(context, 5)
    CGContextMoveToPoint(context, 50, 50)
    CGContextAddLineToPoint(context,100, 200)
    CGContextStrokePath(context)

    // now add the circle on at the line edges

        var point = CGPoint(x:50 , y:50)
        point.x -= 5.0/2
        point.y -= 5.0/2
        var circle = UIBezierPath(ovalInRect: CGRect(origin: point, size: CGSize(width: 5.0,height: 5.0)))
        circle.fill()

        point = CGPoint(x:100 , y:200)
        point.x -= 5.0/2
        point.y -= 5.0/2
        circle = UIBezierPath(ovalInRect: CGRect(origin: point, size: CGSize(width: 5.0,height: 5.0)))
        circle.fill()

    }

目前显示以下图片，

我希望显示如下的工具提示，

有没有人知道如何识别这个特定的点被点击，以及我将如何显示工具提示。 我正在寻找一个快速的解决方案。

Answer 1

定义一个结构来保存你必须触摸的点，以及要显示的文本：

struct TouchPoint {
    var point: CGPoint // touch near here to show a tooltip
    var tip: String // show this text when touched
}

然后在你定义UIView的{​​{1}}子类中，在某处保留它们：

drawRect

var touchPoints: [TouchPoint] = [] // where we have to touch and what tooltip to show 可以多次调用，所以每次都要重新开始：

drawRect

您需要检测UIView上的点击，因此通过更改其初始化来添加手势识别器：

override func drawRect(rect: CGRect) {
    touchPoints = []
    // ...
    // add a touchPoint for every place to touch
    touchPoints.append(TouchPoint(point: point, tip: "point 1"))
}

然后你需要一种方法来查看触摸是否接近接触点，并显示正确的工具提示：

required init?(coder aDecoder: NSCoder) {
    // standard init for a UIView wiht an added gesture recognizer
    super.init(coder: aDecoder)
    addGestureRecognizer(UITapGestureRecognizer(target: self, action: Selector("touched:")))
}

并偶然使用新版本的func touched(sender:AnyObject) { let tapTolerance = CGFloat(20) // how close to the point to touch to see tooltip let tipOffset = CGVector(dx: 10, dy: -10) // tooltip offset from point let myTag = 1234 // random number not used elsewhere guard let tap:CGPoint = (sender as? UITapGestureRecognizer)?.locationInView(self) else { print("touched: failed to find tap"); return } for v in subviews where v.tag == myTag { v.removeFromSuperview() } // remove existing tooltips let hitPoints:[TouchPoint] = touchPoints.filter({CGPointDistance($0.point, to: tap) < tapTolerance}) // list of tooltips near to tap for h in hitPoints { // for each tooltip to show let f = CGRect(origin: h.point+tipOffset, size: CGSize(width: 100, height: 20)) // fixed size label :-( let l = UILabel(frame: f) l.tag = myTag // just to be able to remove the tooltip later l.text = h.tip // draw the text addSubview(l) // add the label to the view } } func CGPointDistanceSquared(from: CGPoint, to: CGPoint) -> CGFloat { return (from.x - to.x) * (from.x - to.x) + (from.y - to.y) * (from.y - to.y) } func CGPointDistance(from: CGPoint, to: CGPoint) -> CGFloat { return sqrt(CGPointDistanceSquared(from, to: to)) } 运算符在+上执行向量添加：

CGPoint

这对我来说没问题。额外的调整是从文本字符串计算UILabel大小，并移动UILabel使其不会从边缘的UIView侧面运行。祝你好运！